Conduit with erosion resistant bend and method of conveying particle-bearing fluids



Sept. 3, 1963 JANSSEN 3102,556

C. A. CONDUIT WITH EROSION RESISTANT BEND AND METHOD OF CONVEYING PARTICLE-BEARING FLUIDS Filed Feb. 10, 1960 INVENTOR CORNELIUS A. JANSSEN BY M/ HIS ATTORNEY United States Patent 3,102,555 CONDUIT WITH EROSION RESISTANT BEND AND METHOD OF CQNVEYING PARTICLE-BEARING FLUIDS Cornelius A. Janssen, Delft, Netherlands, assignor to Shell Oil Company, a corporation of Delaware Filed Feb. 10, 1960, Ser. No. 7,844 Claims priority, application Netherlands June 22, 1959 6 Claims. (Cl. 138-178) The invention relates to conduits having angularly related upstream and downstream sections forming a bend, e.g., a T-bend, and adapted for conveying fluid containing particles, such as a gas or liquid bearing solid particles. It is, more particularly, concerned with an improvement for reducing the erosion to such conduits.

It is known that when fluid media flow or stream along walls are subjected to eddy currents at localities of changes of direction. This leads to erosion of the duct walls when such media carry particles, e.g., iron ore, metal oxide catalyst, or sand entrained in air, not only by impact of the particles on the outer wall which faces the approaching stream but additionally on portions of the downstreamsection. Such erosion is encountered in those regions of such walls wherein the fluid boundary layer adjacent the will is diminished by any irregularity. Consequently, the life of bends in conduits is greatly impaired and repairs or renewal are necessary after a relatively short operating time. This additionally involves repeated shutdowns of the conduits and, to avoid shutdown of associated plant equipment, it is necessary to duplicate the aiiected conduit sections, which is costly.

Attempts have been made to extend the life of such bends by extending the upstream or approach section to provide a dead end beyond the juncture with the downstream section and joining the latter to the former at the desired angle, e. g., at right angles, at a point set back from the dead end. A moderate improvement in the life of the bend was achieved by such a construction, but this did not solve the difiiculty because erosion still occurred at the beginning of the downstream section.

It is the object of the invention to provide an improved bend in conduits wherein erosion is further minimized, particularly in the downstream section of the bend.

It was now found that a much [greater extension in the life of the bend is attained by the construction according to the invention, which includes a closed chamber forming a prolongation of the upstream conduit section beyond its juncture with the angularly disposed downstream section, said chamber being elongated along the downstream section and in free communication with the end of the up stream section and with the side of the downstream section along the latter.

The life of such a bend was found to be at least ten times that of a bend with a simple extension of the upstream conduit section beyond its juncture with the downstream section, and at least a hundred times that of a conventional bend consisting of angularly disposed sections joined at their ends.

The invention will be further described with reference to the accompanying drawing forming a part of this specification and showing two preferred embodiments, wherein:

FIGURE 1 is a perspective view of a bend according to the invention;

FIGURE 2 is a longitudinal section through the bend;

FIGURE 3 is a transverse section taken on the line 3---3 of FIGURE 2; and

FIGURE 4 is a longitudinal section showing a modified construction.

Referring to FIGURES 1-3, the bend includes an upstream conduit section 5 and a downstream section 6 disposed in any desired angular relation thereto, e.g.,

3,102,556 Patented Sept. 3, 1963 making a angle therewith and having its axis in the plane of the upstream section, although the invention is applicable also to bends which make larger or smaller changes in the flow direction. These sections may be circular in cross section and of like diameters, as shown, although these features are not essential. A closed chamber 7 is mounted to form a prolongation of the upstream section and is elongated along the downstream section; it is in free communication with the end of the upstream section and with the side of the downstream section through an opening 8 in the latter. The upstream edge wall 9 of the chamber at the upstream end of the downstream section may be curved to conform to the contour of the upstream section, as is evident from FIG- URE l.

The depth of the chamber, measured from the longitudinal section of the downstream section 6 to the end wall 10 of the chamber, preferably is at least six times the hydraulic radius of the upstream section, i.e., three times the simple radius if it is circular as shown. Further, the length of the chamber in the direction of the axis of the downstream section, measured from the upstream edge wall 9 to the downstream edge wall 11, is also at least six times the said hydraulic radius.

In the modified construction shown in. FIGURE 4, a different angular relation between the upstream and down stream sections 15 and 16 is shown and the end wall 20 of the chamber is curved at its downstream end 22 so that the latter is convergent to the axis of the downstream section. :Other parts corresponding to those described for the first embodiment by numbers, are denoted by corresponding numbers increased by ten.

Although circular conduit sections were shown the invention is also applicable to conduits of other, e:g., rectangular, cross section.

The construction according to the invention is suitable for use in conduits through which gases laden with solid particles are transported, for instance fluidized, finely divided solids such as catalyst, sand, ore, and coal, and for conducting liquid streams containing suspended solid particles, for instance, drilling mud containing abrasive rock.

I claim as my invention:

1. In the method of conveying a particle-bearing fluid with change in flow direction which comprises flowing said fluid through a closed conduit which includes iangula rly related straight upstream and downstream sections having juxtaposed ends, said sections forming an angular bend and being in free and direct intercommunication at said ends over the entire areas thereof, the walls of said sections at the inside of said bend being continuous and conjoined, the improvement of reducing erosion due to said particles by providing a chamber elongated along the downstream section at the outside of said bend and extending outwardly beyond the downstream section wall at the outside of said bend, said chamber being situated in part opposite the said end of the upstream section and extending thence downstream along the downstream section beyond the limits of said upstream section, being in communication with said downstream section at the outside of the bend substantially throughout the length of the chamber, and being otherwise closed.

2. A continuous, closed conduit for conveying fluid which carries particles, said conduit including an upstream section having an end juxtaposed in angular relation to the end of a downstream section to form a band, said ends being in free and direct intercommunication and the walls of said sections at the inside of said bend being continuously straight and conjoined and of substantially uniform cross sectional area, and a chamber situated along the downstream section at the outside of said bend, said chamber extending outwardly beyond the downstream section wall at the outside of the bend and being 3 V in communication only with the downstream conduit section at the outside of the bend opposite the said end of the upstream section and substantially continuously in a downstream direction to a point beyond the limits of said upstream section, said chamber being otherwise closed.

3. A conduit as defined in claim 2 wherein said chamber has a depth, measured from the longitudinal axis of the downstream section to its extremity beyond the end of the upstream section, of :at least six times the hydraulic radius of the upstream section.

4. A conduit as defined in claim 2 wherein the length of said chamber, measured in the direction of the axis of said idownstream section, is at least six times the hydraulic radius of the upstream section.

5. A conduit as'defined in claim 4 wherein said chamber has a depth, measured from the longitudinal axis of the downstream section-to its extremity beyond theend of the upstream section, of at least six times the hydraulic radius of the upstream section.

6. A conduit as defined in claim 2 wherein said chamber includes a downstream Wall which extends to the downstream conduit section at the downstream extremity of the chamber and an end wall opposite the end of the upstream conduit section which is convergent toward the axis of the downstream section in the downstream direction of the latter and which merges with said downstream wall of the chamber.

References Cited in the file of this patent UNlTED STATES PATENTS 610,066 Kuser Aug. 30, 1898 942,139 Green Dec. 7, 1909 1,137,556 Von Glahn Apr. 27, 1915 1,351,573 Hopwood Aug. 31, 1920 2,154,223 Wade Apr. 11, 1939 2,351,642 Starret June 20, 1944 2,486,780 'Fenberg Nov. 1,1949 2,550,186 Clamp Apr..24, 1951 2,837,810 Ekholm June 10, 1958 FOREIGN PATENTS 7,505 Great Britain May 19, 1915 272,588 Great Britain June 13, 1927 287,971 Great Britain May 8, 1928 318,142 Great Britain Oct. 22, 1930 579,215 Germany June 22, 1933 

2. A CONTINUOUS, CLOSED CONDUIT FOR CONVEYING FLUID WHICH CARRIES PARTICLES, SAID CONDUIT INCLUDING AN UPSTREAM SECTION HAVING AN END JUXTAPOSED IN ANGULAR RELATION TO THE END OF A DOWNSTREAM SECTION TO FORM A BAND, SAID ENDS BEING IN FREE AND DIRECT INTERCOMMUNICATION AND THE WALLS OF SAID SECTIONS AT THE INSIDE OF SAID BEND BEING CONTINUOUSLY STRAIGHT AND CONJOINED AND OF SUBSTANTIALLY UNIFORM CROSS SECTIONAL AREA, AND A CHAMBER SITUATED ALONG THE DOWNSTREAM SECTION AT THE OUTSIDE OF SAID BEND, SAID CHAMBER EXTENDING OUTWARDLY BEYOND THE DOWNSTREAM SECTION WALL AT THE OUTSIDE OF THE BEND AND BEING IN COMMUNICATION ONLY WITH THE DOWNSTREAM CONDUIT SECTION AT THE OUTSIDE OF THE BEND OPPOSITE THE SAID END OF THE UPSTREAM SECTION AND SUBSTANTIALLY CONTINUOUSLY IN A DOWNSTREAM DIRECTION TO A POINT BEYOND THE LIMITS OF SAID UPSTREAM SECTION, SAID CHAMBER BEING OTHERWISE CLOSED. 